swiftSC4

Let me start off by saying that the car is a 1996 SC 400 and the problem that I am having is that the battery is discharging. The first obvious place to look for a solution was in replacing the alternator. So. After getting the remanufactured unit from O"Reilly I installed it and the same issue exists. The car at this point is outputting about 10 volts and idle surging. So off goes the alternator and they bench test it to find that the alternator is ok. Alternator goes back on the car and still no luck. We ohmed out the 150 amp ALT fuse that you have to unbolt as well as the ALT TRACE 7.5 amp fuse and all are ok. Check continuity from the B+ cable on the alternator to battery positive check good with low resistance (~0.2 ohms) as well. Jumper cable the ground from battery to engine to see if it might be a ground. Still no luck. At a loss here no idea where to look next. Ideas?

used2be

I'm not knowledgable about the electronics, and you seem to have covered the electrical system pretty fully. If the battery had some plates/cell starting to fail, could that limit the voltage it would accept and the alternator would limit its output? Perhaps run the battery through some tests?

Ali SC3

iTrader: (10)

thread moved. any maintenance or other issue problems not related to brakes suspension go in the performance/maintenance section so please post there next time.

once a battery fully discharges below like 10v or so it usually damages some cells, and while it may recharge to 12v on a charger, the real test is to let is sit for a day and then check and see what its at, or if you are in a hurry apply a small load to and it will loose that extra charge almost immediately. the dead cells will basically give up (like on the first crank if its connected), and then the voltage would jump down and you will see what the battery can actually hold with its good cells. if its in the 10-11 with car on and working alternator then that is not good. I would try a fresh battery or at least throw it on a charger and see if it can even get above 11V anymore. I know I have wrecked a few batterys cranking away in the cold before.

make sure your power steering does not leak and mess up your new alternator, another sc400 problem.

swiftSC4

Yeah we had replaced the power steering pump prior to the alternator. The original alternator tested bad on the bench. With a freshly charged and good battery it drags it down to 12.2 volts. So. We are going to warranty this one with a new one and see what happens. Anybody have a wiring diagram of the regulator pins? I guess checkingtthat connector is next if this does not work. Also wondering if the PCM might send the excite signal to the regulator as well.

swiftSC4

The regulator plug has 3 wires 2 of which (ENGINE fuse and TRACE ALT fuse as well) have power with the key on. The IGN fused circuit at the regulator connector does not have power with the key on. The battery light which is also on the same wire does not come on with the key on either. This all based off page 5 off this pdf link. http://www.v-eight.com/images/Images...%20Diagram.pdf that is the one we used.